Large shift current in cubic and hexagonal LiZn$X$ semiconductors

Abstract

The rectified bulk photovoltaic effect (BPVE) in noncentrosymmetric semiconductors, also called shift current, is considered a promising alternative to the conventional p-n junction based solar cell applications. A clear understanding of the shift current mechanism and search for materials with large shift current is, therefore, of immense interest. ABC semiconductors LiZnX (X = N, P, As and Sb) can be stabilized in cubic as well as hexagonal morphologies lacking inversion symmetryan ideal platform to investigate the significant contributing factors to shift current, such as the role of structure and the chemical species. Using density-functional calculations properly accounting for the electronic bandgaps, the shift current conductivities in LiZnX (X = P, As, Sb) are found to be approximately an order of magnitude larger than the well-known counterparts and peak close to the maximum solar radiation intensity. Notably, hexagonal LiZnSb shows a peak shift current conductivity of ∼ 75 µA/V 2 , comparable to highest predicted values in literature. Our comparative analysis of the shift current response not only posits Li-Zn-based ABC semiconductors as viable material candidates for potential applications, but also elucidates the structure-BPVE relationship and paves way for accelerated development in this direction.